Problem - When the slave was disconnected from the master, under certain 
          conditions, upon reconnect, it will report that it received a 
          packet larger the slave_max_allowed_packet which causes the
          replication to stop.
 
Analysis -The reason of this failure is that on reconnect
          the slave sets the max_allowed_packet from the master's mi->mysql
          object which keeps the max_allowed_packet as 1MB. This causes the 
          slave to report such error on recieving packet bigger than 1MB. 
          START SLAVE on the slave fixes the problem since it restarts
          slave threads which initializes the max_allowed_packet to
          slave_max_allowed_packet.
      
Fix - The problem is fixed by some code refactoring and introduction of a new
      function which updates the max_allowed_packet for the THD object of the
      slave thread and the mysql->options max_allowed_packet.